It is not an exaggeration to say that many hundreds of dieting techniques have been proposed based on different and varied principles, some sound and others not so sound and even damaging. The fundamental principle on which every sound method of dieting is based is that, in order to lose weight the caloric intake must be less than the energy output of the individual.
However, this relationship between the expenditure and the intake of energy is asymmetric and thus, for example, in order to expend the caloric intake added to the body consequent to eating a single slice of bread, it would be necessary for the individual to walk approximately one kilometer. The conclusion, therefore, is that increasing the energy expenditure, by means of exercise, is not itself sufficient to lose weight and that limiting the caloric intake by eating less is essential. This having been said, such a formula is problematic because the amount of food which is required is a function of appetite and even hunger of the individual.
What is required, therefore, is some way of controlling the mouth of the would-be dieter. Possibly the best form of control would be for the diet instructor to stand by the dieter for 24 hours a day and to warn him when he has eaten enough and to instruct him, at that point, to stop eating. Clearly, such an ideal solution is impractical. It would, however, clearly be desirable to propose an alternative method approximating such an approach.